mast step integrity
A friend of mine who is not a professional boat builder, yet is a capable boat owner, recently had a similar problem on an ODay which he aquired as a second boat. His solution was to fabricate a tool which allowed him to dig out a significant amount of rotten core material in the deck area surrounding the forward hatch. He then stuffed fiberglass material into the void, and was careful to insert "spacers" of appropriate thickness to keep the layers from compressing under a load. He also made up a steel plate for the mast step which helps bear the load there. He's confident now that he has a good solid cabin structure free of rot. Depending on how comfortable you are with working with fiberglass etc., this may or may not seem like a good solution for your application. As in all these exchanges, I make no claims to be any sort of expert, so you have to judge for yourself. Best wishes as you proceed.
